Each kind of machine may be said to do a kind of work. Work is also a tern—and a very important one.
Work done by humans can be primary, such as moving a pile of earth with a shovel or winding up a clock; or it can be secondary work, such as adding up an invoice, doing a crossword puzzle, calculating the results of a management decision when the full dynamics of the system are known, or setting the hands of the clock.
This distinction has been made in other words many times before, but "tertiary work" is a less familiar concept. It includes making aesthetic judgements, such as choosing a wallpaper for a room, or choosing a pair of spectacle frames that suit you, or making moral decisions. The human abilities required by secondary work and by tertiary work are different. For example, it is quite possible to have enough musical aptitude to be able to distinguish between two piano performances of a piece and to describe the differences, but yet not be able to say which is the better performance, even though more able critics might be unanimous in their judgement on the question.
Stewart, D J. A ternary domanial structure as a basis for cybernetics and its place in knowledge. Kybernetes 18, 4, 19-28, 1989.